Help transmission 1996 Deville

Help I have a 96 Deville Iím getting code PO741 Mr. transmission this code would not make the car not shift. Is that true would the car computer give me two codes? The transmission shop just called they are saying the car has a hold lot of codes coming up. One is cc some they don't know what that is I know it had a ckt proformance. someone please help !!!

The shop called today the codes are pcm ecr pitln pcn po741.
They want $810. for labor they don't know what parts the car will need. The mess up on Friday 01/02/04 the computer said service emissions system message I park my car on tueday I get drive down the road on my way to the shop to have the emissions serviced the service transmission message come on for the first time.